This invention relates to sputtering processes. More particularly, it relates to a process for the sputter polishing of thin film devices.
In the construction of thin film devices wherein a passivating and insulating film such as silicon dioxide is sputter-deposited on a patterned metal layer, it has been found that the passivating film tends to follow the contours of the deposited metal pattern. Quite often when it is desired to provide maximum protection for the metal film, a process known as resputtering is resorted to, resputtering being the positive ion bombardment of the passivating film during its deposition. It has been found that such resputtering improves the quality of the sputter-deposited film.
It has also been found, however, that an excessive amount of resputtering in the sputter deposition of a silicon dioxide passivating film may sputter etch the edge of a metal stripe prior to the stripe's being covered with the film. In the resputtering process, there may also occur the sputter-etching of slope surfaces of the silicon dioxide film, the slope surfaces being those which follow the contours of the underlying metal. In addition, there may be deposition on the flat surfaces of the film.
In the production of thin film multilevel devices, it is highly desirable to produce planar or as near planar surfaces as is possible of each passivating film layer as successive levels are added to the device.
Accordingly, it is an important object of this invention to provide a method for sputter polishing passivating and insulating films in thin film devices to produce a relatively planar surface on the passivating film.
It is another object to provide a process in accordance with the preceding object wherein there is prevented the sputter-etching of the edges of the metal stripes on which the film is being deposited during the film's deposition.